Study On Frequency Domain Dielectric Characteristics Of Transformer Oil-paper Insulation Aging Based On Dissado-Hill Relaxation Model

The stable operation of the power grid is an important guarantee to ensure the normal life of the people and the rapid development of the national economy.Therefore the power transformer plays a vital role in it.Because the power transformers are subjected to the combined stress aging effects of heat,electricity and vibration during long-term operation,insulation of the power transformer reliability has been severely tested.Therefore,it is necessary to in-depth study of methods to detect the insulation status of power transformers to achieve a non-destructive quantitative assessment of the insulation status of the transformer.Studies have shown that the frequency domain dielectric response test is easily affected by the ambient temperature,which changes the frequency domain dielectric response characteristics of oil-paper insulation.At the same time,different excitation amplitudes will also affect the frequency domain dielectric response test.In order to eliminate the influence of test temperature and excitation amplitude,paper studies the frequency domain characteristics of transformer oil-paper insulation aging based on the Dissado-Hill relaxation model and combined with frequency-temperature translation theory and Garton effect.In order to study the frequency domain characteristics of transformer oil-paper insulation aging,paper carried out an accelerated thermal aging test of oil-paper insulation,and built a frequency domain dielectric response test system.Under the effect of accelerated thermal aging at 130°C,6 XY equivalent models of oil-paper insulation under different aging conditions were selected.Then the frequency domain dielectric response test was carried out at different test temperatures and excitation amplitudes respectively,which obtained frequency domain dielectric response test results of oil-paper insulation.Paper use the frequency-temperature translation theory and the Garton theory to eliminate the influence of test temperature error and excitation amplitude on the frequency domain dielectric response test.Then the Dissado-Hill relaxation model is used to analyze the frequency domain dielectric response test results of oil-paper insulation under different aging conditions.The characteristic parameters of the Dissado-Hill relaxation model are extracted,the functional relationship is quantified between the characteristic parameters and the influencing factors.The analysis of the test results through the Dissado-Hill relaxation model shows that the aging degree of oil-paper insulation and test temperature are positively correlated with the movement intensity of the inner clusters of the oil-paper insulation,and negatively correlated with the inner clusters of the oil-paper insulation.The greater the excitation amplitude,the stronger inter-cluster movement and intra-cluster movement in the oil-paper insulation.In order to quantitatively analyze the influence of the aging degree of oil-paper insulation,test temperature and different excitation amplitudes on the frequency domain dielectric response test,the characteristic parameters of the Dissado-Hill relaxation model are extracted according to the Dissado-Hill equivalent circuit model.They establish the corresponding exponential function equation with the degree of polymerization of the insulating paperboard,test temperature and excitation amplitude respectively.Which has certain reference significance for the evaluation of oil-paper insulation aging.